The molecular pathology of acute myeloid leukemia

GDF11 level and its effect on prognosis in patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the proliferation of CD34 positive self-renewing malignant hematopoietic stem cells. Previous studies have shown that the transforming growth factor beta (TGFβ) pathway plays a role in AML pathogenesis, especially by affecting the microenvironment. Growth differentiation factor 11 (GDF11) is a member of the TGFβ superfamily, involved in embryological development and known as rejuvenating factor. In this study, our aim was to determine the serum GDF11 level in patients with AML, to compare it with the control group, to determine its relationship with follistatin, vimentin, and E-cadherin levels, and to determine whether GDF11 influences AML prognosis. Serum GDF11, vimentin, follistatin, and E-cadherin levels of newly diagnosed or relapsed/refractory AML patients and age- and gender-matched control group were measured by enzyme-linked immunosorbent assay. Serum GDF11 level was higher in the patient group (263.87 ± 126.54 ng/L) compared to the control group (211.54 ± 61.47 ng/L; p = 0.035). GDF11 level did not change according to age, gender, hemoglobin level, and bone marrow blast rate. No correlation was found between GDF11 level, response rates, and survival status of the patients. A positive correlation was detected between GDF11, E-cadherin, and vimentin levels. As a conclusion, increased serum GDF11 levels in AML patients may be linked to the regeneration ability of leukemic stem cells. There is a need for studies investigating GDF11 expression in myeloblasts.

OSR1 suppresses acute myeloid leukaemia cell proliferation by inhibiting LGR5-mediated JNK signalling

Odd-skipped related transcription factor 1 (OSR1) is implicated in various pathophysiologic processes, such as embryonic heart and urogenital formation, and functions as a tumour suppressor in diverse tumours. Regardless, the regulatory role and mechanism of OSR1 in acute myeloid leukaemia are scarce. Firstly, the CD34-positive blasts or the normal blasts were isolated from the plasma samples of acute myeloid leukaemia patients or healthy donors, respectively. Expression of OSR1 analysis by western blot and qRT-PCR showed that OSR1 was reduced in CD34-positive blasts and acute myeloid leukaemia cell lines. Secondly, acute myeloid leukaemia cell lines were transfected with pcDNA vector or shRNA for the over-expression or silence of OSR1, respectively. Functional assays demonstrated that ectopic expression of OSR1 decreased cell viability and repressed the proliferation of acute myeloid leukaemia cells, while promoted the cell apoptosis. Silence of OSR1 contributed to the proliferation of acute myeloid leukaemia cells and suppressed the cell apoptosis. Thirdly, over-expression of OSR1 decreased protein expression of leucine-rich-repeat-containing G-protein-coupled receptor 5 (LGR5) and JNK phosphorylation in the acute myeloid leukaemia cells. Ectopic expression of LGR5 attenuated OSR1 over-expression-induced decrease of LGR5 and JNK phosphorylation. Lastly, ectopic expression of LGR5 attenuated OSR1 over-expression-induced decrease of cell viability and proliferation in acute myeloid leukaemia cells. In conclusion, OSR1 functioned as a tumour suppressor in acute myeloid leukaemia cells by inhibiting LGR5-mediated activation of JNK signalling.

Molecular Action of Polyphenols in Leukaemia and Their Therapeutic Potential

Leukaemia is a malignant disease of the blood. Current treatments for leukaemia are associated with serious side-effects. Plant-derived polyphenols have been identified as potent anti-cancer agents and have been shown to work synergistically with standard chemotherapy agents in leukaemia cell lines. Polyphenols have multiple mechanisms of action and have been reported to decrease cell proliferation, arrest cell cycle and induce apoptosis via the activation of caspase (3, 8 and 9); the loss of mitochondrial membrane potential and the release of cytochrome c. Polyphenols have been shown to suppress activation of transcription factors, including NF-kB and STAT3. Furthermore, polyphenols have pro-oxidant properties, with increasing evidence that polyphenols inhibit the antioxidant activity of glutathione, causing oxidative DNA damage. Polyphenols also induce autophagy-driven cancer cell death and regulate multidrug resistance proteins, and thus may be able to reverse resistance to chemotherapy agents. This review examines the molecular mechanism of action of polyphenols and discusses their potential therapeutic targets. Here, we discuss the pharmacological properties of polyphenols, including their anti-inflammatory, antioxidant, anti-proliferative, and anti-tumour activities, and suggest that polyphenols are potent natural agents that can be useful therapeutically; and discuss why data on bioavailability, toxicity and metabolism are essential to evaluate their clinical use.

Efficacy of 10-day decitabine in acute myeloid leukemia

The azanucleotide decitabine is used in the treatment of acute myeloid leukemia (AML). Studies have shown conflicting results with 10-day regimens used in previously untreated AML patients. Additionally, there is little data on 10-day decitabine regimens in the relapsed setting. This study investigated outcomes of 108 adult patients with AML in the upfront and relapsed setting treated with a 10-day decitabine regimen. In the upfront group, the overall response rate (ORR, CR + CRi) was 36.1% and the median overall survival (OS) was 6.6 months, while the relapsed/refractory group had an ORR of 25% with an OS of 4.8 months. When analyzed with respect to cytogenetics, the upfront group featured an ORR of 28.1% with an OS of 9.4 months in the intermediate cytogenetic cohort compared to a 40.5% ORR and an OS of 5.4 months in the unfavorable cytogenetic cohort. An analysis of the relapsed/refractory group demonstrated an ORR of 26.3% with an OS of 7.9 months for intermediate cytogenetics versus 25.0% with an OS of 1.8 months in the unfavorable cohort. While these response rates are similar to previously published data, the median OS appears shorter.

Birth Weight and Subsequent Risk of Total Leukemia and Acute Leukemia: A Systematic Review and Meta-Analysis

Objective: Birth weight, an important indicator of fetal nutrition and degree of development, may affect the risk of subsequent leukemia. At present, little is known about the effect of birth weight on acute myeloid leukemia (AML) and whether there is a dose-dependent relationship of birth weight with acute lymphoid leukemia (ALL) and AML. To address these questions, the present work aimed to systematically investigate the relationship between birth weight and the risk of subsequent leukemia based on the current epidemiological studies Methods: Relevant studies were systematically retrieved from electronic databases PubMed, Embase, and Cochrane Library, from inception to May 15th, 2021. Finally, 28 studies (including 21 case-control studies and 7 cohort studies) were included for the final meta-analysis. Results in cohort studies were performed by risk ratios (RRs), while those in case-control studies by odds ratios (ORs), and all results were assessed by adopting the random-effect model. Besides, a dose-dependent analysis was conducted based on the cohort studies. Results: Compared with the population with normal birth weight (NBW), the population with high birth weight (HBW) might have an increased risk of leukemia (OR 1.33, 95%CI 1.20-1.49; I ² 0%). Meanwhile, low birth weight (LBW) was associated with a decreased risk of ALL, as evidenced from the pooled analysis of case-control studies (OR 0.83, 95% CI 0.75-0.92; I ² 23.3%). However, relative to NBW population, the HBW population might have an increased risk of ALL (OR 1.28, 95% CI 1.20-1.35; I ² 7%). There was no obvious evidence supporting the relationship between LBW and the risk of AML from the pooled analysis of case-control studies (OR, 1.11 95% CI 0.87-1.42; I ² 31.7%). Conclusions: Overall, in children and young adults, HBW population may be associated with the risks of subsequent leukemia and AML relative to NBW population, but the supporting dose-dependent evidence is lacking. In addition, compared with NBW population, there is stronger evidence supporting a significantly increased risk of subsequent ALL in HBW population, and a decreased risk in LBW population in a dose-dependent manner. More prospective studies with large samples are warranted in the future to validate and complement these findings.

Therapeutic targeting of FLT3 and associated drug resistance in acute myeloid leukemia

Acute myeloid leukemia (AML) is a heterogeneous disease caused by several gene mutations and cytogenetic abnormalities affecting differentiation and proliferation of myeloid lineage cells. FLT3 is a receptor tyrosine kinase commonly overexpressed or mutated, and its mutations are associated with poor prognosis in AML. Although aggressive chemotherapy often followed by hematopoietic stem cell transplant is the current standard of care, the recent approval of FLT3-targeted drugs is revolutionizing AML treatment that had remained unchanged since the 1970s. However, despite the dramatic clinical response to targeted agents, such as FLT3 inhibitors, remission is almost invariably short-lived and ensued by relapse and drug resistance. Hence, there is an urgent need to understand the molecular mechanisms driving drug resistance in order to prevent relapse. In this review, we discuss FLT3 as a target and highlight current understanding of FLT3 inhibitor resistance.

The loss or absence of minimal residual disease of <0·1% at any time after two cycles of consolidation chemotherapy in CBFB-MYH11-positive acute myeloid leukaemia indicates poor prognosis

No consensus has been reached on the relationship between CBFB-MYH11 copies and prognosis. Of 1525 acute myeloid leukemia (AML) patients, 58 with CBFB-MYH11-positive AML (16/58 patients with c-kit mutation) were retrospectively analyzed with a median follow-up duration of 29.8 (range: 4.8-74.4) months. Of these, 25/58 (43.1%) patients underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT), 10 of whom had the c-kit mutation. Of the 33 patients who did not undergo allo-HSCT, recurrence in patients with CBFB-MYH11/ABL level >0.1% at any time after two consolidation cycles was significantly higher than in patients with CBFB-MYH11/ABL level <0.1% (61.9% vs. 0%, P = 0.001); further, the 3-year relapse-free survival (RFS; 31.4% vs. 100%, P = 0.004) and event-free survival (EFS; 33.1% vs. 100%, P = 0.004) were significantly decreased in patients with CBFB-MYH11/ABL level >0.1% at any time after two consolidation cycles. The 3-year RFS and EFS rates were lower in patients who did not receive allo-HSCT than in those who did (31.4% vs 84.6%, P = 0.000; 31.4% vs. 80.8%, P = 0.001). CBFB-MYH11-positive AML patients with CBFB-MYH11/ABL level >0.1% at any time after two cycles of consolidation had poor prognoses, and allo-HSCT could improve their survival.

The Novel Phospholipid Mimetic KPC34 Is Highly Active Against Acute Myeloid Leukemia with Activated Protein Kinase C

Acute myeloid leukemia (AML) is an aggressive malignancy with poor outcomes. Nucleoside analogs are subject to resistance mechanisms including downregulation of equilibrative nucleoside transporter (ENT1) and deoxycytidine kinase (dCK). KPC34 is a novel phospholipid mimetic that when cleaved by phospholipase C (PLC) liberates gemcitabine monophosphate and a diacylglycerol mimetic that inhibits the classical isoforms of protein kinase C (PKC). KPC34 acts independently of ENT1 and dCK. KPC34 was active against all AML cell lines tested with IC₅₀s in the nanomolar range. Enforced expression of PLC increased response to KPC34 in vivo. In an orthotopic, xenograft model, KPC34 treatment resulted in a significant increase in survival compared to control animals and those treated with high-dose cytarabine. In a PDX model with activated PKC, there was a significant survival benefit with KPC34, and at progression, there was attenuation of PKC activation in the resistant cells. In contrast, KPC34 was ineffective against a syngeneic, orthotopic AML model without activated PKC. However, when cells from that model were forced to express PKC, there were significantly increased sensitivity in vitro and survival benefit in vivo. These data suggest that KPC34 is active against AML and that the presence of activated PKC can be a predictive biomarker.

Current and Future Molecular Targets for Acute Myeloid Leukemia Therapy

OPINION STATEMENT

Acute myeloid leukemia (AML) disease prognosis is poor and there is a high risk of chemo-resistant relapse for both young and old patients. Thus, there is a demand for alternative and target-specific drugs to improve the 5-year survival rate. Current treatment mainstays include chemotherapy, or mutation-specific targeting molecules including FLT3 inhibitors, IDH inhibitors, and monoclonal antibodies. Efforts to devise new, targeted therapy have included recent advances in methods for high-throughput genomic screening and the availability of computer-assisted techniques for the design of novel agents predicted to specifically inhibit mutant molecules involved in leukemogenesis. Crosstalk between the leukemia cells and the bone marrow microenvironment through cell surface molecules, such as the integrins αvβ3 and αvβ5, might influence drug response and AML progression. This review article focuses on current AML treatment options, new AML targeted therapies, the role of integrins in AML progression, and a potential therapeutic agent-integrin αvβ3 antagonist.

Acute myeloid leukemia with KMT2A-SEPT5 translocation: A case report and review of the literature

Chromosomal rearrangement involving the KMT2A gene is one of the most common genetic alteration in acute myeloid leukemia. A total of 135 different KMT2A rearrangements have been identified, where 94 translocation partner genes are now characterized at the molecular level. Of these 94 translocation partner genes, 35 translocation partner genes occur recurrently, but only 9 specific gene fusions account for more than 90% of cases. Translocation of KMT2A with SEPT5 gene at 22q11.2 is rare, with few reported cases in the literature. In this report, we are presenting a case of KMT2A-SEPT5 fusion in de novo acute myeloid leukemia with t(11;22)(q23;q11.2) with a review of the literature.

Dysfunctional diversity of p53 proteins in adult acute myeloid leukemia: projections on diagnostic workup and therapy

The heterogeneous nature of acute myeloid leukemia (AML) and its poor prognosis necessitate therapeutic improvement. Current advances in AML research yield important insights regarding AML genetic, epigenetic, evolutional, and clinical diversity, all in which dysfunctional p53 plays a key role. As p53 is central to hematopoietic stem cell functions, its aberrations affect AML evolution, biology, and therapy response and usually predict poor prognosis. While in human solid tumors TP53 is mutated in more than half of cases, TP53 mutations occur in less than one tenth of de novo AML cases. Nevertheless, wild-type (wt) p53 dysfunction due to nonmutational p53 abnormalities appears to be rather frequent in various AML entities, bearing, presumably, a greater impact than is currently appreciated. Hereby, we advocate assessment of adult AML with respect to coexisting p53 alterations. Accordingly, we focus not only on the effects of mutant p53 oncogenic gain of function but also on the mechanisms underlying nonmutational wtp53 inactivation, which might be of therapeutic relevance. Patient-specific TP53 genotyping with functional evaluation of p53 protein may contribute significantly to the precise assessment of p53 status in AML, thus leading to the tailoring of a rationalized and precision p53-based therapy. The resolution of the mechanisms underlying p53 dysfunction will better address the p53-targeted therapies that are currently considered for AML. Additionally, a suggested novel algorithm for p53-based diagnostic workup in AML is presented, aiming at facilitating the p53-based therapeutic choices.

New Insights in the Cytogenetic Practice: Karyotypic Chaos, Non-Clonal Chromosomal Alterations and Chromosomal Instability in Human Cancer and Therapy Response

Recently, non-clonal chromosomal alterations previously unappreciated are being proposed to be included in cytogenetic practice. The aim of this inclusion is to obtain a greater understanding of chromosomal instability (CIN) and tumor heterogeneity and their role in cancer evolution and therapy response. Although several genetic assays have allowed the evaluation of the variation in a population of cancer cells, these assays do not provide information at the level of individual cells, therefore limiting the information of the genomic diversity within tumors (heterogeneity). The karyotype is one of the few available cytogenetic techniques that allow us not only to identify the chromosomal alterations present within a single cell, but also allows us to profile both clonal (CCA) and non-clonal chromosomal alterations (NCCAs). A greater understanding of CIN and tumor heterogeneity in cancer could not only improve existing therapeutic regimens but could also be used as targets for the design of new therapeutic approaches. In this review we indicate the importance and significance of karyotypic chaos, NCCAs and CIN in the prognosis of human cancers.

Oral Azacitidine (CC-486) for the Treatment of Myelodysplastic Syndromes and Acute Myeloid Leukemia

The myelodysplastic syndromes (MDS) comprise a heterogeneous group of clonal myeloid malignancies characterized by multilineage cytopenias, recurrent cytogenetic abnormalities, and risk of progression to acute myeloid leukemia (AML). AML, which can occur de novo as well as secondary to MDS, is characterized by malignant clones of myeloid lineage in the bone marrow and peripheral blood, with dissemination into tissues. The cytidine nucleoside analog and epigenetic modifier azacitidine is approved in the U.S. for the treatment of all French-American-British subtypes of MDS and in many countries for the treatment of AML with 20%-30% blasts and multilineage dysplasia according to the World Health Organization classification. Benefits of azacitidine treatment of patients with AML with >30% blasts have also been shown in a recent phase III trial. Oral administration of azacitidine may enhance patient convenience, eliminate injection-site reactions, allow for alternative dosing and scheduling, and enable long-term treatment. Phase I studies with oral azacitidine (CC-486) have shown biological activity, clinical responses, and tolerability in patients with MDS and AML. Extended dosing schedules of oral azacitidine (for 14 or 21 days of 28-day cycles) are currently under investigation as frontline therapy in patients with lower risk MDS, as maintenance therapy for patients with AML not eligible for stem cell transplant, and as maintenance therapy for patients with MDS or AML following stem cell transplant. This review presents clinical data supporting the use of injectable azacitidine in MDS and AML and examines the rationale for and results of the clinical development of oral azacitidine.

The inherent metastasis of leukaemia and its exploitation by sonodynamic therapy

Nearly all cancers are linked by the inexorable phenotype of metastasis as malignant growths have the capability to spread from their place of origin to distant sites throughout the body. While different cancers may have various propensities to migrate towards specific locations, they are all linked by this unifying principal. Unlike most neoplasms, leukaemia has inherent cell motility as leukocytes are required to move throughout the vascular system, suggesting that no mutations are required for anchorage independent growth. As such, it seems likely that leukaemias are inherently metastatic, endowed with the deadliest phenotype of cancer simply due to cell of origin. This article presents the biology of metastasis development and how leukaemia cells are inherently provided these phenotypic characteristics. It is then proposed how clinicians may be able to exploit the motility of leukaemia and metastatic emboli of other cancer types through an approach known as sonodynamic therapy (SDT), a treatment modality that combines chemotherapeutic agents with ultrasound to preferentially damage malignant cells. As experimental evidence has indicated, SDT is a promising therapeutic approach in need of clinical testing for further validation.

Tumor suppressor DYRK1A effects on proliferation and chemoresistance of AML cells by downregulating c-Myc

Acute myeloid leukemia (AML), caused by abnormal proliferation and accumulation of hematopoietic progenitor cells, is one of the most common malignancies in adults. We reported here DYRK1A expression level was reduced in the bone marrow of adult AML patients, comparing to normal controls. Overexpression of DYRK1A inhibited the proliferation of AML cell lines by increasing the proportion of cells undergoing G0/G1 phase. We reasoned that the proliferative inhibition was due to downregulation of c-Myc by DYRK1A, through mediating its degradation. Moreover, overexpression of c-Myc markedly reversed AML cell growth inhibition induced by DYRK1A. DYRK1A also had significantly lower expression in relapsed/refractory AML patients, comparing to newly-diagnosed AML patients, which indicated the role of DYRK1A in chemoresistance of AML. Our study provided functional evidences for DYRK1A as a potential tumor suppressor in AML.

Animal models of leukemia: any closer to the real thing?

Animal models have been invaluable in the efforts to better understand and ultimately treat patients suffering from leukemia. While important insights have been gleaned from these models, limitations must be acknowledged. In this review, we will highlight the various animal models of leukemia and describe their contributions to the improved understanding and treatment of these cancers.

Integrative analysis of prognostic factors in Chinese core binding factor leukemia

The characteristics of core binding factor (CBF) leukemia appear to differ between Chinese and Caucasian patients. In this study, we analyzed the biological and clinical characteristics of 76 Chinese CBF leukemia patients out of 425 newly diagnosed acute myeloid leukemia (AML) patients. The frequency of CBF AML was 17.9%. Patients harboring t(8;21) were predominant in CBF AML. The incidence of c-kit mutation in CBF AML was 28.9%. The N822K mutation appeared to be more prevalent in Chinese CBF AML patients. Multivariate analysis showed that c-kit mutation and high white blood cell count could negatively impact overall survival (OS) (HR=2.74 and 6.24, P=0.007 and 0.022, respectively) but did not affect relapse-free survival (RFS). Kaplan-Meier analysis showed a significant difference in both OS and RFS between wild-type and mutated c-kit patients. Although we had included recently reported prognostic indicators in our analysis, our results demonstrated that only c-kit mutation and high white blood cell count had prognostic impact on Chinese CBF AML patients.

Unique dual targeting of thymidylate synthase and topoisomerase1 by FdUMP[10] results in high efficacy against AML and low toxicity

Acute myeloid leukemia (AML) is an aggressive malignancy that leads to marrow failure and death. There is a desperate need for new therapies. The novel fluoropyrimidine, FdUMP[10], was highly active against both human AML cell lines, (IC(50) values, 3.4nM-21.5nM) and murine lines (IC(50) values, 123.8pM-131.4pM). In all cases, the IC(50) of FdUMP[10] was lower than for cytarabine and ∼ 1000 times lower than 5-fluorouracil (5-FU). FdUMP[10] remained effective against cells expressing the Flt3 internal tandem duplication, BCR-ABL, MN1, and an shRNA against p53. It had activity against patient samples at concentrations that did not affect normal hematopoietic cells. FdUMP[10] inhibited thymidylate synthase (TS) and trapped topoisomerase I cleavage complexes (Top1CCs), leading to DNA damage and apoptosis. All cell lines and nearly all primary AML samples examined expressed both TS and Top1. In vivo, FdUMP[10] was active against a syngeneic AML model with a survival advantage equivalent to doxorubicin plus cytarabine. 5-FU treatment was toxic and did not improve survival. FdUMP[10] was better tolerated than 5-FU or cytarabine plus doxorubicin and did not affect normal HSCs, while 5-FU dramatically impaired their ability to engraft. In summary, FdUMP[10] was highly efficacious and better tolerated than standard therapies.

JTE-607, a multiple cytokine production inhibitor, induces apoptosis accompanied by an increase in p21waf1/cip1 in acute myelogenous leukemia cells

Proinflammatory cytokines and growth factors have been thought to play crucial roles in the pathology of acute myelogenous leukemia (AML) by supporting the proliferation and survival of AML cells in an autocrine and paracrine manner, although further elucidation is required. JTE-607 was originally identified as a multiple cytokine inhibitor that suppresses production of proinflammatory cytokines from lipopolysaccharide (LPS)-stimulated peripheral blood mononuclear cells. Herein, we report that JTE-607 exhibits inhibitory activity on the growth of AML cell lines accompanying reduction of the proinflammatory cytokine and growth factor production. In in vitro studies, JTE-607 suppressed expression and production of cytokines, which are spontaneously up-regulated in AML cell lines. JTE-607 also abrogated proliferation of AML cells in a concentration range in which colony formation of normal bone marrow cells was not affected. The growth inhibition by JTE-607 was characterized by induction of cell-cycle arrest at the S-phase and apoptosis, accompanied by a decrease in c-Myc and increase in p21(waf1/cip1). In a leukemia model engrafted with U-937 cells, JTE-607 significantly prolonged survival in mice and reduced human cytokine mRNA levels in the bone marrow. These results suggest the usefulness of JTE-607 in therapeutic applications for patients with hypercytokinemia and aggressive AML cell proliferation.

Prevalence of FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD+) in de novo acute myeloid leukemia patients categorized according to cytogenetic risk

CONTEXT AND OBJECTIVE

The mechanism involved in leukemogenesis remains unclear and more information about the disruption of the cell proliferation, cell differentiation and apoptosis of neoplastic cells is required.

DESIGN AND SETTING

Cross-sectional prevalence study at the Discipline of Hematology, Hospital São Paulo, Universidade Federal de São Paulo.

METHODS

We investigated FMS-like tyrosine kinase 3/internal tandem duplication (FLT3/ITD+) in 40 adult patients with de novo acute myeloid leukemia (AML), categorized according to cytogenetic results, from September 2001 to May 2005.

RESULTS

Thirteen patients (32.5%) were classified as presenting the favorable karyotype, 11 patients (27.5%) as an intermediate group, 7 patients (17%) as an undefined group and 9 patients (22.5%) as the unfavorable group. FLT3/ITD+ was found in 10 patients (25%): 3 with FLT3/ITD+ and favorable karyotype; 4 with FLT3/ITD+ and intermediate karyotype; 2 with FLT3/ITD+ and undefined karyotype; and only 1 with FLT3/ITD+ and unfavorable karyotype. Among the patients without FLT3/ITD+, 10 presented favorable karyotype, 8 intermediate, 4 undefined and 8 unfavorable karyotype. The cytogenetic results showed no correlations between FLT3/ITD presence and the prognostic groups (P = 0.13). We found that 2 patients were still alive more than 24 months later, FLT3/ITD+ did not influence the patients' survival rate.

CONCLUSION

We found the same frequency of AML with FLT3/ITD+ in both the favorable and intermediate prognosis groups. Only one patient presented AML, FLT3/ITD+ and unfavorable karyotype (the hypothetical worst clinical situation). Therefore, the prognostic advantage of favorable cytogenetics among patients with FLT3/ITD+ remains to be elucidated, for it to be better understood.

Identical outcome after autologous or allogeneic genoidentical hematopoietic stem-cell transplantation in first remission of acute myelocytic leukemia carrying inversion 16 or t(8;21): a retrospective study from the European Cooperative Group for Blood and Marrow Transplantation

PURPOSE

Patients with acute myelocytic leukemia carrying inversion 16 (inv16) or t(8;21) have a better initial response to high-dose cytarabine than patients without these chromosomal abnormalities. They presently do not undergo transplantation in first remission (CR1), but there is concern about late relapses.

PATIENTS AND METHODS

From 1990 to 2004, 325 adult patients received transplantations in CR1 (159 patients with inv16 and 166 patients with t(8;21), including 35 and 60 patients, respectively, with additional chromosomal abnormalities). Genoidentical allografts were performed in 64 patients with inv16 and 81 patients with t(8;21), and autografts were performed in 95 patients with inv16 and 85 patients with t(8;21).

RESULTS

In patients with inv16, after allogeneic and autologous transplantation, the 5-year leukemia-free survival (LFS) rates were 59% and 66% (P = .5), the relapse incidence (RI) rates were 27% and 32% (P = .45), and the transplantation-related mortality (TRM) rates were 14% and 2% (P = .003), respectively. Female patients had a lower RI and a higher LFS. Additional chromosomal abnormalities, compared with no additional abnormalities, were associated with lower RI rate (12% v 34%, respectively; P = .01) and higher 5-year LFS rate (78% v 59%, respectively; P = .04). In patients with t(8;21), after allogeneic and autologous transplantation, the 5-year LFS rates were 60% and 66% (P = .69), the RI rates were 15% and 28% (P = .03), and the TRM rates were 24% and 6% (P = .003), respectively. Younger age and a lower WBC count at diagnosis were associated with a lower TRM and a better LFS. The TRM was lower and the RI was higher in patients with autologous transplantations versus allogeneic transplantations.

CONCLUSION

Both autologous and allogeneic transplantation resulted in similar outcomes.

From dissection of disease pathogenesis to elucidation of mechanisms of targeted therapies: leukemia research in the genomic era

Leukemia is a group of heterozygous diseases of hematopoietic stem/progenitor cells that involves dynamic change in the genome. Dissection of genetic abnormalities critical to leukemia initiation provides insights into the elusive leukemogenesis, identifies distinct subsets of leukemia and predicts prognosis individually, and can also provide rational therapeutic targets for curative approaches. The past three decades have seen tremendous advances in the analysis of genotype-phenotype connection of leukemia, and in the identification of molecular biomarkers for leukemia subtypes. Intriguingly, differentiation therapy, targeted therapy and chemotherapy have turned several subtypes of leukemia from highly fatal to highly curable. The use of all-trans retinoic acid and arsenic trioxide, which trigger degradation of PML-RARalpha, the causative fusion protein generated by t (15;17) translocation in acute promyelocytic leukemia (APL), has led to a dramatic improvement of APL clinical outcome. Imatinib mesylate/ Gleevec/STI571, which inhibits the tyrosine kinase activity of BCR-ABL oncoprotein, has now become the new gold standard for the treatment of chronic myeloid leukemia. Optimal use of chemotherapeutic agents together with a stringent application of prognostic factors for risk-directed therapy in clinical trials has resulted in a steady improvement in the treatment outcome of acute lymphoblastic leukemia. Hence, the pace of progress extrapolates to a prediction of leukemia control in the twenty-first century.

HOX deregulation in acute myeloid leukemia

The deregulation of homeobox (HOX) genes in acute myeloid leukemia (AML) and the potential for these master regulators to perturb normal hematopoiesis is well established. To date, overexpression of HOX genes in AML has been attributed to specific chromosomal aberrations and abnormalities involving mixed-lineage leukemia (MLL), an upstream regulator of HOX genes. The finding reported in this issue of the JCI by Scholl et al. that caudal-type homeobox transcription factor 2 (CDX2), which is capable of affecting HOX gene expression during embryogenesis, is overexpressed in 90% of patients with AML and induces a transplantable AML in murine models provides an alternative mechanism for HOX-induced leukemogenesis and yields important insights into the hierarchy of HOX gene regulation in AML (see the related article beginning on page 1037).

Gene-expression profiling identifies distinct subclasses of core binding factor acute myeloid leukemia

Core binding factor (CBF) leukemias, characterized by either inv(16)/t(16;16) or t(8;21), constitute acute myeloid leukemia (AML) subgroups with favorable prognosis. However, there exists substantial biologic and clinical heterogeneity within these cytogenetic groups that is not fully reflected by the current classification system. To improve the molecular characterization we profiled gene expression in a large series (n = 93) of AML patients with CBF leukemia [(inv (16), n = 55; t(8;21), n = 38)]. By unsupervised hierarchical clustering we were able to define a subgroup of CBF cases (n = 35) characterized by shorter overall survival times (P = .03). While there was no obvious correlation with fusion gene transcript levels, FLT3 tyrosine kinase domain, KIT, and NRAS mutations, the newly defined inv(16)/t(8;21) subgroup was associated with elevated white blood cell counts and FLT3 internal tandem duplications (P = .011 and P = .026, respectively). Supervised analyses of gene expression suggested alternative cooperating pathways leading to transformation. In the "favorable" CBF leukemias, antiapoptotic mechanisms and deregulated mTOR signaling and, in the newly defined "unfavorable" subgroup, aberrant MAPK signaling and chemotherapy-resistance mechanisms might play a role. While the leukemogenic relevance of these signatures remains to be validated, their existence nevertheless supports a prognostically relevant biologic basis for the heterogeneity observed in CBF leukemia.

Molecular profiling reveals myeloid leukemia cell lines to be faithful model systems characterized by distinct genomic aberrations

To model and investigate different facets of leukemia pathogenesis, a widely accepted approach is to use immortalized leukemia cell lines. Although these provide powerful tools to our knowledge, few studies have addressed the question whether hematopoietic cell lines represent accurate and reliable model systems. To improve the molecular characterization of these model systems, we analyzed 17 myeloid leukemia cell lines using DNA microarray technology. By array-based comparative genomic hybridization, we identified recurrent genomic DNA gains and losses, as well as high-level amplifications. Parallel analysis of gene expression helped delineate potential candidate genes, and unsupervised analysis of gene expression data revealed cell lines to cluster in part based on underlying cytogenetic abnormalities. Comparison with clinical leukemia specimens showed that key signatures were retained, as myeloid cell lines with characteristic cytogenetic aberrations co-clustered with leukemia samples carrying the respective abnormality. Signatures were also quite robust, as expression data from cell lines correlated highly with published data. Thus, our analyses demonstrate myeloid cell lines to exhibit conserved and stable signatures reflecting the underlying primary cytogenetic aberrations. Our refined molecular characterization of myeloid cell lines supports the utility of cell lines as faithful and powerful model systems and provides additional insights into the molecular mechanisms of leukemogenesis.